Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2019	$ 171,799	$ 75	$ 20,227	$ 2,819	$ 148,678
Beginning Balance, shares at Dec. 31, 2019		7,514
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards	904	$ 1	903
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards, shares		56
Common stock repurchased on vesting of restricted stock units and performance awards	(378)		(378)
Common stock repurchased on vesting of restricted stock units and performance awards, shares		(6)
Share-based compensation expense	342		342
Company repurchase of common stock	(2,987)	$ (1)	(169)		(2,817)
Company repurchase of common stock, shares		(59)
Cash dividends on common stock	(2,262)				(2,262)
Unrealized loss on investments, net of tax	(2,735)			(2,735)
Net (loss) income	(3,407)				(3,407)
Ending Balance at Mar. 31, 2020	161,276	$ 75	20,925	84	140,192
Ending Balance, shares at Mar. 31, 2020		7,505
Beginning Balance at Dec. 31, 2020	198,235	$ 76	24,885	7,564	165,710
Beginning Balance, shares at Dec. 31, 2020		7,566
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards	815		815
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards, shares		38
Common stock repurchased on vesting of restricted stock units and performance awards	(107)		(107)
Common stock repurchased on vesting of restricted stock units and performance awards, shares		(1)
Share-based compensation expense	1,060		1,060
Company repurchase of common stock	(3,436)		(170)		(3,266)
Company repurchase of common stock, shares		(49)
Cash dividends on common stock	(2,278)				(2,278)
Unrealized loss on investments, net of tax	(5,250)			(5,250)
Net (loss) income	(4,554)				(4,554)
Ending Balance at Mar. 31, 2021	$ 184,485	$ 76	$ 26,483	$ 2,314	$ 155,612
Ending Balance, shares at Mar. 31, 2021		7,554